Xbox support apparently can do nothing to help. But for starters, the game is Steam Deck verified, and user reports on ProtonDB for the game are pretty good. Part of the frustration seems to be that neither the Forza nor Xbox support teams can delete this data on a player's behalf. It also potentially highlights a weakness within the Xbox cloud system itself, but that's a discussion for another day. A cloud sync issue should not be able to block a player from playing the game they paid for.